ProSoft Technology inRAX MVI56E-MNETCR User Manual page 100

Reference
User Manual
Normal Data Transfers
Normal data transfer includes the paging of the user data and status data found
in the module's internal database in registers 0 to 4999. These data are
transferred through read (input image) and write (output image) blocks. The
following topics describe the function and structure of each block.
Block Response from Module to Processor
These blocks of data transfer information from the module to the ControlLogix
processor. The following table describes the structure of the input image.
Offset
0
1 to 40
41
The Read Block ID is an index value used to determine the location of where the
data will be placed in the ControlLogix processor controller tag array of module
read data. Each transfer can move up to 40 words (block offsets 1 to 40) of data.
In addition to moving user data, the block also contains status data for the
module.
The Write Block ID associated with the block requests data from the ControlLogix
processor. Under normal program operation, the module sequentially sends read
blocks and requests write blocks.
For example, if the application uses three read and two write blocks, the
sequence will be as follows:
R1W1→R2W2→R3W1→R1W2→R2W1→R3W2→R1W1→
This sequence will continue until interrupted by other write block numbers sent by
the controller or by a command request from a node on the Modbus network or
operator control through the module's Configuration/Debug port.
Block Request from Processor to Module
These blocks of data transfer information from the ControlLogix processor to the
module. The following table describes the structure of the output image.
Offset
0
1 to 40
41
The Write Block ID is an index value used to determine the location in the
module's database where the data will be placed. Each transfer can move up to
40 words (block offsets 1 to 40) of data.
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Modbus TCP/IP Multi Client Enhanced Communications Module for Remote Chassis
Description
Write Block ID
Read Data
Read Block ID
Description
Write Block ID
Write Data
Spare
MVI56E-MNETCR ♦ ControlLogix Platform
Length
1
40
1
Length
1
40
1
ProSoft Technology, Inc.
June 14, 2011